Emmanuel Lochin

Prof. Emmanuel Lochin received his Ph.D from the LIP6 laboratory of Pierre and Marie Curie University - Paris VI in December 2004 and the Habilitation Thesis (Habilitation à Diriger des Recherches) in October 2011 from Institut National Polytechnique de Toulouse (INPT). From July 2005 to August 2007, he held a researcher position in the Networks and Pervasive Computing research program at National ICT Australia, Sydney. He joined ISAE in September 2007 as researcher and network security officer. He is member of TéSA laboratory and networking expert in the TeSA scientific committee.

His research interests are mainly related to transport protocols and congestion control.

Research

TETRYS enables a new reliability algorithm specifically useful when retransmission is either problematic or not possible. In case of multimedia or multicast communications and in the context of the Delay Tolerant Networking (DTN), the classical retransmission schemes can be counterproductive in terms of data transfer performance or not possible when the acknowledgment path is not always available. Indeed, over long delay links, packets retransmission has a meaning of cost and must be minimized. The purpose of Tetrys is to propose a novel reliability mechanism with an implicit acknowledgment strategy that could be used either within these new DTN proposals, for multimedia traffic or in the context of multicast transport protocols. This proposal is based on a new on-the-fly erasure coding concept specifically designed to operate efficient reliable transfer over bi-directional links. Tetrys allows to unify a full reliability with an error correction scheme. Tetrys is not sensitive to the loss of acknowledgments while ensuring a faster data availability to the application compared to other traditional acknowledgment schemes. See this paper for detail :

Among the different transport protocols providing a LBE service, Low Extra Delay Background Transport (LEDBAT) is the most used. LEDBAT is a delay-based congestion control protocol that has been standardized by the Internet Engineering Task Force (IETF). LEDBAT aims to exploit the remaining capacity while limiting the queuing delay around a predefined target which may be set up to 100 ms according to RFC 6817. Consequently, LEDBAT flows limits the amount of queuing delay introduced in the network and thus lower their impact on best-effort flows such as TCP.
Despite being a widely deployed protocol, the two main LEDBAT parameters (i.e., target and gain) have been revealed to be complex to determine as their tuning highly depends on the network conditions and not dynamically configurable.
Indeed, LEDBAT may become more aggressive than TCP in case of misconfiguration.

Our protocol, FLOWER (Fuzzy LOWer-than-Best-EffoRt Transport Protocol), is a promising alternative of LEDBAT.
With FLOWER, we aim to overcome the LEDBAT shortcomings while still fulfilling its goals. The principal difference with LEDBAT is that FLOWER replaces the linear P-type controller (proportional controller) of LEDBAT by a fuzzy controller to modulate the congestion window.

FLOWER code is based on LEDBAT and TCP Vegas ns-2 implementations and is available for ns-2 and GNU/Linux here :

FLOWER protocol ns-2 and Linux codes

Jungle Networking

Recent theoretical works, investigating the possibility to dispense the Internet with end-to-end congestion control, demonstrate that this new paradigm seems to be sustainable for the Internet and would not lead to a congestion collapse. Unlike congestion-controlled networks that depend on end-hosts to achieve the max-min-fairness, over anarchical networks, the traffic assignment is network based. This allows to be robust to network attacks or misbehaving end-hosts. However, the price of this anarchy is that loss recovery should be done with an ideal erasure coding scheme.

In this context we propose DeCongestion Transport Protocol (DCTP), a transport protocol based on Tetrys erasure coding scheme to perform over anarchical networks. We evaluate this protocol over a realistic ISP topology and show
that : 1) the efficiency of such networks remains close to TCP ; 2) they support small buffer size which is a key property for optical networks and 3) real-time flows can be supported while reducing the end-to end-delay in the case of small buffer size.

Honors and Awards

I am, with Guillaume Jourjon and Patrick Sénac, the recipient of the best paper award of the Multimedia Communications & Home Services Symposium of IEEE International Conference on Communications (IEEE ICC 2007)
Glasgow, UK - 24-27 June, 2007